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 Mobile ViewAIR CONDITIONING & HEAT PUMP SYSTEMS A/C - HEAT PUMP CONTROLS & SWITCHES AIR CONDITIONER BTU CHART AIR CONDITIONER COMPONENT PARTS AIR CONDITIONER TYPES, ENERGY SOURCES AIR CONDITIONER NOT WORKING AIR FILTERS for HVAC SYSTEMS AIR HANDLER / BLOWER UNITS BACKUP HEAT for HEAT PUMPS BLOWER DOORS & AIR INFILTRATION BLOWER FAN CONTINUOUS OPERATION BLOWER FAN OPERATION & TESTING BOOKSTORE - Air Conditioning "How To" Books CAPACITORS for HARD STARTING MOTORS CAPILLARY TUBES CHINESE DRYWALL HAZARDS CIRCUIT BREAKER SIZE for A/C or HEAT PUMP CLEANING & Legionella BACTERIA CHINESE DRYWALL HAZARDS COMBUSTION GASES & PARTICLE HAZARDS COMPRESSOR & CONDENSING COIL, A/C CONDENSATE HANDLING, A/C CONDENSATION or SWEATING PIPES, TANKS COOL OFF HEAT Thermostat Switch COOLING CAPACITY, RATED COOLING COIL or EVAPORATOR COIL COOLING LOAD REDUCTION by ROOF VENTS COMBUSTION GASES & PARTICLE HAZARDS CONDENSATE HANDLING, A/C CONDENSATION or SWEATING PIPES, TANKS DATA TAGS on AIR CONDITIONERS DEFINITION of Heating & Cooling Terms DEHUMIDIFICATION PROBLEMS DEW POINT CALCULATION for WALLS DEW POINT TABLE - CONDENSATION POINT GUIDE DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP DIAGNOSE & FIX HEATING PROBLEMS-BOILER DIAGNOSE & FIX HEATING PROBLEMS-FURNACE DUCT SYSTEM & DUCT DEFECTS AIR FILTERS for HVAC SYSTEMS ALLOY SYSTEMS FLEXDUCT ASBESTOS HVAC DUCTS ASBESTOS PAPER on DUCTWORK ASBESTOS TRANSITE DUCTWORK BALANCING AIR DUCT FLOW DUCT & AIR HANDLER ODORS DUCT DAMAGE, MECHANICAL DUCT INSULATION - Asbestos Paper DUCT ROUTING & SUPPORT DUST CONTAMINATION FROM HVAC? FIBERGLASS DUCT, RIGID CONSTRUCTION FIBERGLASS HVAC DUCTS FIRE DAMPERS in DUCTWORK FLOOD DAMAGE in DUCT WORK GOODMAN GRAY FLEXDUCT INCREASING RETURN AIR LEAKY DUCT CONNECTIONS LOCATION OF REGISTERS & DUCTS MOLD in AIR HANDLERS & DUCT WORK NOISES in DUCT SYSTEM ODORS in AIR HANDLERS & DUCT WORK OWENS CORNING FLEXDUCT OWL FLEXDUCT RETURN AIR REGISTERS & DUCTS SOUNDPROOFING for DUCTWORK SUPPLY DUCTS & REGISTERS TRANSITE PIPE AIR DUCTS UNDERSIZED RETURN DUCTS UNSAFE DUCT OPENINGS VIBRATION DAMPENERS WATER & ICE IN DUCT WORK Convection Condensate Leaks into Ductwork External Leaks into Ducts Flood-Exposed HVAC Ducts WET CORRODED DUCT WORK ZONE DAMPER CONTROLS DUST CONTAMINATION FROM HVAC? EDUCATION, HVAC SCHOOLS ELECTRIC MOTOR DIAGNOSTIC GUIDE ELECTRIC MOTOR OVERLOAD RESET SWITCH ELECTRICAL POWER SWITCH FOR HEAT EVAPORATIVE COOLING SYSTEMS EVAPORATOR COIL or COOLING COIL EXPANSION VALVES, REFRIGERANT FAN, AIR HANDLER BLOWER UNIT FAN AUTO ON Thermostat Switch FAN, COMPRESSOR/CONDENSER UNIT FAN CONVECTOR HEATERS - HYDRONIC COILS FAN LIMIT SWITCH FAN NOISES FURNACES WARM AIR HEATING SYSTEMS GAS EXPOSURE EFFECTS, TOXIC GAS DETECTION & MEASUREMENT GAUGE, REFRIGERATION PRESSURE TEST HEAT LOSS (or GAIN) in buildings HEAT PUMPS HUMIDITY LEVEL TARGET INDOOR AIR QUALITY IMPROVEMENT GUIDE INSPECTION CHECKLIST - OUTDOOR UNIT INSPECTION LIMITATIONS, A/C SYSTEMS LOST COOLING CAPACITY MANUALS & PARTS GUIDES - HVAC MOTOR OVERLOAD RESET SWITCH NOISE AIR CONDITIONER / HEAT PUMP NOISE / SOUND DIAGNOSIS & CURE OPERATING COST OPERATING DEFECTS OPERATING TEMPERATURES PORTABLE ROOM AIR CONDITIONERS PRESSURE READINGS, REFRIGERANT REPAIR GUIDE, AIR CONDITIONERS / HEAT PUMPS REPAIR & DIAGNOSTIC FAQs for A/C REFRIGERANTS RETROFIT SIZING for A/C or HEAT PUMPS SEER RATINGS & OTHER DEFINITIONS SOLAR ENERGY SYSTEMS SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS SWAMP COOLERS SYSTEM OPERATION THERMOSTATS, HEATING / COOLING THERMOSTATIC EXPANSION VALVES WATER COOLED AIR CONDITIONERS More Information |
Here we discusses the problems of condensation, water, or ice formation in heating or air conditioning system duct work. InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website. Causes of Condensation, Water or Ice Formation in Duct Work, What Happens, How to Prevent Condensate, Icing, Leaks in & From DuctsWarm Indoor Air Convection Currents Entering Cool HVAC Ducts
Readers should also see WET CORRODED DUCT WORK and see FROST BUILD-UP on AIR CONDITIONER COILS where we describe build-up of ice on the cooling coil in air conditioning air handler units. Also see TRANSITE PIPE AIR DUCTS where we describe flooding of HVAC ductwork in slabs. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. In freezing climates such as New York where some homes route their top floor HVAC ducts along the attic floor, sometimes that ductwork is not well insulated and just as it gets too hot in summer (increasing the cost of air conditioning), in winter the same ducts become too cold, increasing heating costs. But something else funny can happen in homes with attic ducts that are used only for air conditioning. One of our clients called us to investigate a claim that had resulted in litigation against the company who had installed a new roof on their home. The owner claimed that the roof was leaking. The roofer claimed that the roof was perfect. What was curious was that the roof "leaked" only at the end of winter, and at times when there had been no rain and when there was no melting snow on the rooftop. What we observed was the following causes of ice in the air ducts:
The duct ice problem was occurring because warm moist air was circulating by convection during winter, rising up into both the supply and return registers, flowing through the duct work, and leaking out of an open air handler. As the warm moist air entered the attic, the ducts were absolutely freezing cold. Moisture first condensed, then formed ice inside the duct system. Ice accumulated in the duct system throughout the winter a little at a time, until it was several inches thick. When the weather warmed all that ice in the ducts melted and leaked back out into the upper floor in a stunning flood. The owners, who were not thinking particularly clearly about whether or not it was raining or whether or not there was melting snow on the roof, saw that it was "raining inside" out of their air conditioning ducts and through other ceiling locations (since the ducts were not water tight there was leakage out of the ducts at other areas besides just at the supply and return air registers. The solution to this problem had these components:
The roofing contractor was happy with this solution and the building owner was relieved as well. Perhaps because their roof had previously been leaking, before it was replaced, when they saw water coming through their top floor ceilings they thought that it was still leaking. Of course the ice in ducts problem won't occur in homes which use the same duct system for winter heating, nor will it occur in climates where freezing weather is uncommon, though we still might see some surprising in-duct condensation in some cases. Water or Condensate Leaks into HVAC DuctworkWater leaks into rooftop commercial ducts are common if the ducts were not properly installed and sealed against the weather. Especially when duct insulation is located inside of the HVAC ducts water leaking into the system invites mold and pathogenic growth in the HVAC system.
Our photos show water stains on duct interior insulation (above left) and ponding on a tar-coated rooftop commercial HVAC duct system (above right). Central HVAC humidifiers may also leak into air handlers and ductworkIf you are using a central humidifier, typically turned on during dry winter months, be sure that it is not leaking onto your furnace heat exchanger - a source of costly damage and potentially a dangerous rust hole and heat exchanger leak of carbon monoxide into building air. An improperly located or mal-adjusted central humidifier can blow excessive moisture into the HVAC duct system, a potential source of duct damage or mold growth in the air handling system. Central Air Conditioning Cooling Coil Condensate May also leak into air handlers and ductworkIt's common, especially in very humid areas, for condensate to blow off of the cooling coil and into the HVAC duct system. See BLOWER LEAKS, RUST & MOLD for details. As reader Joe Hartoebben pointed out, this problem may be more serious if the air handler's condensate drain pan and drain piping are not working properly as the combination of high humidity (typical for example in Florida) and inadequate condensate handling will invite the blower to send condensate water droplets blowing down the duct system. Building Floods May Include HVAC Ducts
Question: I Fixed Condensation Problems in my HVAC Ducts, but Now I Have Metal Chimney Condensation To CureFirst I must thank you for your article on condensation in conditioner ducts that are in the attic and not used for heating (WATER & ICE IN DUCT WORK). I had the same problem as in your article and had several AC techs and a P.E. look at the problem and not one of them could come up with answer. Since I blocked the return and register grills the problem disappeared. Perhaps you could suggest an answer to another problem. I have a gas boiler and a separate gas hot water heater in the basement. I have a metal chimney into which they are connected. The chimney goes up through the roof. The chimney extends about three feet below where the boiler flue and gas flue are connected. I am getting condensation dripping out of the bottom of the chimney pipe - there is not a large amount and it appears to be coming down the inside of the chimney and then leaking out. Any suggestions? Thank you for your help. F. D. - Mattituck NY Check These Chimney Safety Worries FirstA competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem. That said, here are some things to consider:
Watch Out: I'm afraid that those conditions are likely to be unsafe and could include a carbon monoxide hazard - so be sure you've got working CO detectors Questions & Answers regarding this articleQuestions & answers about the detection, cause, effects, and cure of water or ice formation or flooding in HVAC ducts. Ask a Question or Search InspectAPediaHTML Comment Box is loading comments...
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